The present invention relates generally to the review of a semiconductor wafer for defects and more particularly to a novel method and system for reviewing a semiconductor wafer for defects at a review station using at least one defect sampling condition.
Integrated circuits (ICs) are commonly manufactured through a series of processing steps. Very often more than a hundred processing steps are performed to produce a properly functioning integrated circuit chip.
A semiconductor material, commonly in the shape of a wafer, serves as the substrate for integrated circuits. Semiconductor ICs are typically manufactured as an assembly of a hundred or more chips on a single semiconductor wafer which is then cut up to produce the individual IC chips. Typically, a wafer made of silicon is used as the integrated circuit substrate, the silicon wafer being approximately 150-300 mm in diameter and 0.6-1 mm thick. During the manufacturing process, the silicon wafer is first polished and cleaned to remove all contaminant particles situated thereon. The silicon wafer is then treated in preparation for a series of processing steps involving a plurality of photolithographic patterns (also commonly referred to as masks). In the production of integrated circuits, microelectronic circuits are formed onto the silicon wafer through a process of layering. In the layering process, conductive and insulative layers of thin films are deposited and patterned onto the silicon wafer. Each layer is patterned by a mask designed specifically for it, the mask defining the areas within the wafer that are to be treated such as by etching or implanting.
Semiconductor fabrication technology today deals with silicon wafers which are approximately 200 mm in diameter and which feature geometries with dimensions well below 0.5 xcexcm (micrometer). Due to the high complexity and level of integration of integrated circuits, the absence of contaminants on every layer of the wafer is critical in order to realize acceptable levels of product yield. Specifically, the presence of one contaminant particle larger than the half the width of a conductive line on the silicon wafer can result in the complete failure of a semiconductor chip produced from the wafer. Such a chip has to be discarded which thereby decreases the percentage yield per wafer and increases the overall cost of the individual wafers. Therefore, a critical task facing semiconductor process engineers is to identify and, as soon as possible, to eliminate sources of surface contamination on each layer of a semiconductor wafer.
Accordingly, inspection systems are well known in the art and are commonly used to detect, identify and correct yield limiting defects which are introduced onto the surface of a semiconductor wafer during the fabrication process of integrated circuits.
It is well known in the art for a plurality of inspection systems to be used to inspect a semiconductor wafer at various points in time during the fabrication of said semiconductor wafer. As such, each inspection system serves to inspect the semiconductor wafer after the treatment of a particular layer of the integrated circuit. By using multiple inspection instruments to scan various layers of the semiconductor wafer for contaminant particles, the user is able to discern where, and more specifically on which layer, a defect first occurred in the manufacturing process. The ability to discern where a defect first occurred is extremely useful in removing the defect and in preventing future contamination.
However, in order to properly ascertain where in the manufacturing process a defect first occurred, it is necessary to compare all of the defects detected by each inspection system. Accordingly, it is well known in the art to connect to all of the inspection systems used to scan a semiconductor wafer to a data management system server.
One or more data analysis stations are also often connected to the data management system server. Each of the data analysis stations enables the user to perform a series of cursory analysis tests (e.g., trend charts) of the defect data detected by the inspection devices. Although useful, data analysis stations are not capable of determining the class of a particular defect (i.e., what the defect is).
Accordingly, one or more review stations are often connected to the data management system server. A review station is typically in the form of a high magnitude optical microscope which enables the user to closely examine individual defects which are detected by the one or more inspection systems. Specifically, the microscope enables the operator to determine the particular class (i.e., the nature) of each defect.
Typically, a review station receives all of the defect data compiled by a particular inspection system for one particular layer of one particular wafer. The operator is then required to thoroughly examine each individual defect using the optical microscope.
Although well known and widely used in the art, the particular exchange of defect data between the review station and the data management system server as described above suffers a notable drawback. Specifically, the review station receives from the data management system server only those defects which are detected by a particular inspection system for a particular layer of a particular wafer. As a result, the operator is precluded from examining common types of defects which may be present on different layers of the same wafer. As such, the inability of the operator to compare the defect data of multiple layers of wafers renders more difficult the ability to determine when during the fabrication process of a semiconductor wafer recurrent contaminant particles are introduced, which is highly undesirable.
Accordingly, it is known in the art for software to be installed onto the data management system server which creates a central database into which all of the raw historic defect data compiled by the one or more inspection systems are uploaded. In this manner, the operator is able to extract from the database all of the defect data which was detected by a particular inspection system (which is selected by the operator) at a particular point in time (which is selected by the operator), thereby providing the operator with the ability to access any defect which has been detected by the one or more inspection systems, which is highly desirable.
Although useful and well known in the art, the software described above suffers from a notable drawback. Specifically, the operator is required to extract from the database the entire set of defect data which was detected by the selected inspection system at the selected point in time. As a result of the operator""s inability to filter out different types of defect data, a considerably large number of defects are often extracted from the database and are sent to the review station for further examination. In this situation, the operator is required to closely examine each of the relatively large number of defects which are sent to the review station, which is considerably time consuming and labor intensive, which is highly undesirable.
It is an object of the present invention to provide a method and system which includes at least one inspection device for inspecting the one or more semiconductor wafers for defects.
It is another object of the present invention to provide a method and system as described above which includes a data management system server connected to said at least one inspection device, said data management system server storing the raw historic defect data detected by said at least one inspection device.
It is yet another object of the present invention to provide a method and system as described above which includes at least one review station for examining under high magnification individual defects which are stored in said data management system server.
It is still another object of the present invention to provide a method and system as described above in which said review station is able to extract one or more defects which are stored in said data management system server.
Accordingly, there is a system for reviewing at least one layer of at least one semiconductor wafer for defects, said system being interfaced to a first inspection device which scans the at least one layer of the at least one semiconductor wafer for defects, said first inspection device producing a first set of detected defects from scanning the at least one layer of the at least one semiconductor wafer, said system being interfaced to a review station for reviewing the at least one layer of the least one semiconductor wafer, said system comprising a server connected to said first inspection device and said review station, said server comprising a database into which said first set of detected defects is stored, and review client software which interfaces which said review station, said review client software enabling a sample of said first set of detected defects to be extracted from the database using at least one defect sampling condition.
There is also provided a method for inspecting at least one layer of at least one semiconductor wafer for defects using at least one inspection mechanism, said at least one inspection mechanism being connected to a server which includes a database, said server being connected to a review station, said method comprising the steps of scanning the at least one layer of the at least one semiconductor wafer using said at least one first inspection mechanism, said scanning step yielding a first set of detected defects, storing said first set of detected defects into said database, requesting a sample of said first set of detected defects using at least one defect sampling condition, said requesting step being performed at said review station, extracting the sample of said first set of detected defects using at least one defect sampling condition from the database, said extracting step being performed by said server in response to said requesting step, and sending the extracted sample of said first set of detected defects from said server to said review station.
Various other features and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings which form a part thereof, and in which is shown by way of illustration, a specific embodiment for practicing the invention. The embodiment will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. The following detailed description is therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.